Flotation



msnm. son 2,341,046

- Umran- PATENT OFFICE v l asumo l .rametfnmory xirigvli'lnn, lni.||omin to E. I; du Pont de Nemours@ Company;y Wilmingtolnbel., a corporation. of Delaware smaimnsaonas No-Drawinf.. Application October 7, 1940,

3. Claims'.

invention rela-testo an improved process v for the concentration ,of ores, more particularly litrelatestofamethod foraimprovintheemciency 'ot lii'otlzi notation yproteases. employing :cationic .surface active, compounds as4 )notation agents.. `Still more y.po-rtici-llartv' it. relates tothe use vof assisting.: agents yin froth flotation. processes -em pinyin;I cationic surface active-compounds as .notation agents: :and still :more particularly it relates to. :the- .use of assisting. agents comprising water-soluble .protective :colloids of the carbohydrate type in froth .flotation processes for .the

I l-'conoentration of negatively-charged minerals. l'employingfcatimric; surface; active compounds; as

lilotati'cnagents.

'This invention has as an object the development 'of an 'improved method Vfor separating or concentrating negativelycharged .minerals espe- 4 i '.cially quartz and" silicate minerals. A further -obi'ectzis to increase the-.selectivity of cationic .surface actia'e compounds as flotation agents in .,suchprocesses.. Another object is lto provide a.

water-soluble protective colloldof the ycarbohydratetypelas an assisting agentxwhieh in oom.- -lrination with' a cationic surfacel active agent` producesv la synergistic ei'fect thereby imparting to the combination a collecting-power lwhich is greater thanthat ofithe sum of the. elements oi" .saidcombination. A still further object .is the.

production of an improved processl of `concen- :tratinzl carbonate and oxide.v minerals,

using .cationic surface active agents 4as flotation agents. water-soluble protective, colloids of Athe carbohydrate type as; assistants. Asistonts have. been found -topromote separation to iioat` siliceous' minerals by` masons-.ofiV airoth I vin preference to the indinerent: metallic 'oxides and carbonates has been utilized by thisj invention, but the performance of the cationic surface active compound as flotation agentsl has been improved, particularlyl in the` separation.. of

sili'ceous4 lmaterial from calcium carbonate, ory

limestone, .by the use of protective colloids of These asof more of' the s'ill'ceousl material for a 'given amount,v of' flotation agent resulting in the separation of a `higher ,grade .of limestone with the same or higher recoveryl remaining behind as tailings. For example, whentannic acid iszadfd'ed i 'as an assistant. (ExamplefII) to a flotation'operstains from yquartz particles and gives. clean.`

" readily floatedquartz. Thus, i-n the. case of the.

the carbohydrateltype ssassistina agents. other Aobjects-wilt.appearhereinafter.

The above and' other objectsy appearing hereinafter are. accomplished, `by the fouowmgfinvention `which. comprises `adding to a pulp contain .ing :metal carbonate and/or oxide.v minerals and' negatively .charged .sangue material a cationic surface active compound asa notation agent. and- 9,. waterQsoluble protective colloid of the carbohydrate typev as :an assisting agent. and subjectine .the-same to ar froth flotation operation. The

valuable fraction of the ore may 'be found in ,i the froth layer lor it `may remain in the. cell'. In 4this-miras-.asharizyer `separation of valuable .mi-neralrom langue effected., resulting. in a purer product land.:greater recovery.. l l

'Ille ability .of surface-active cationic reagents removal of silica from iron .oxide minerals an improved performance in the collecting properties of cationicI surface active compounds as. flotation agents results from leaching` the ore with a small .amount of. a mineral acid such as hydrochloric acid prior tothe flotation step.

This invention. will be further illustrated but is not intended tov be limited by the following examples:

Example I A sample of siliceous limestone used inthe' production of Portland cement was employed in flotation experiments using assistants with cal tionic surface active compounds as notation reagents. The mineral composition of this limestonel has .beendescribed in detaill `by B. L. Miller and C. H. Breerwood (Am. Inst. Mining Met. Engrs., Tech. Pub. No. 606, p. 15, February, 1935). Calcite, mica. and quartz constitute the bulk. of

. one liter of water and 3 kg. of flint pebbles. The

ore particles were then about 84-36% mesh.

The slurry minus 200 prepared according to the above procedure 'was placed in a I kg. Denver Equipment Company flotation cell of the sub-aeration type. Sufficient water was then added to make a pulp containing approximately -25% solids. The agitator was then started and 14 cc. of an 0.18% water solution of crude dodecyl amine added. Seven hundredths of l hydrochloride was a gram of the frother hereafter referred to vas frother b, was added to induce frothing.y AThe frothing agent consisted of the .branched-chain,

oxygenated organic compounds 'prepared by the catalytic hydrogenation of carbon oxides under elevated temperatures and pressures as described in U. S. Patents 1,844,129, 1,844,857, and 1,939,708. .The boiling range ofthe particular fraction of these oxygenated. organic compoundsused was 147+157 C.

.With .theaddition of. frother b a heavily loaded froth, dark. gray in color, ,formed rapidly andkWas collected for, 9minutes, after .which time there was no further collection of minerals or production of .,froth. The flotation concentrate and tailings were filtered, dried, weighed, and

analyzed for their calcium carbonate content. The results are summarized inthe following table:

O oac'ol '.Rrducts h 40 1 eig t Percent I l Per com' g. recovery y $8,003

Product ight Weight Percent 1, 000.7 l 75.5 755.6 f Per Cent v, 245.7 64.70 159.0 21.1 f g recovery UndetflUW 755.0 79.02 596. 6 7B. 9 I

Overflow. 272.0 43. 07 Underfio'w. 725. 7 88.57

.- IVCalcd.

Magenta-Crude,dodecylamine hydrochloride,l 0.025 g. or0.05 1b./tox 1;irotl1erb,0.07g.or U.l4 1b./ton.

It Will be noted from the table that`78.9% of the calcium carbonateremained in the cell in `the underflow, commonly called the tailings" in ore dressing terminology.v Since the desired mineral concentrated in the underflow I prefer not to use the term tailings'as thatterm generally implies a waste product or gangue. Similarly I use thev term overflow to designate the product carried out of the cell by the froth. Generally the product frothed out of the cell is called the concentrate but I prefer toavoid that term, since in its usual use it connotes a purification or segregation o f valuable minerals and in my process the froth carries out the undesired minerals. i

The terms underflow and overflow. are therefore used to designate my flotation products rather than the commonly used terms tailings and concentrate In" the above experiment the grade of limestone was in creased `from 75.5% to 79.02% of calcium carbonate with a recovery of 78.9%.

By crude dodecylamine hydrochloride as used herein is meant-the mixture of hydrochlorides of the higher primary aliphatic amines in which the alkyl groups correspond in carbon content and composition' to the fatty acids occurring naturally in coconut oil.

Example II The process of Example I was repeated using, in addition to the same quantities of crude dodecylamine hydrochloride and frother b, 0.5 gram of tannic acid. The flotation fractions were filtered, dried, weighed and analyzed as before.- The results of this experiment, using tannic acid as an assistant, are summarized in the following table:

l 20 Rg111 1itc.-Qrnde dodecyl amine hydrochloride. 0.025 g. or 0.05 irother b, 0.07 or 0.14 lb./ton; tannic acid, 0.50 g. or 1.0 Comparison ofthe above results with those of the control run (Example I) shows that a marked improvement has been made by the addition of Itannic acid as indicated by the substantial increase in the grade of the limestone7 represented by the underflow,4 from '79'. 0 2%'t'o'87.81%',01v call cium carbonate in additi'on'to an 'increase' in Irecovery from 78.9% to 82.0%'. .Example III The process ,of Example I was repeated using, in addition to f the same quantities of :crude dodecylamine hydrochloride and ,frotherb'g 0.5018. of pectic "acid corresponding to 1.0 lb.`/ ton of heads. 'I he flotation fractions "were filtered, dried, weighed and analyzed as before.A f Theresults of this experimentare'summariz'ed f ir'the following table: A 1"- Rcagenfsf-Crudc dodecylamine hydrochloride, '0.05 vllbf/ton frother b, 0.14 lb`./ton; pectic acid, l`.0 lb./ton. *'1

A The addition of pectic acid increased'th'e grade of underilow fromv 79.02%, obtained by thecontrol run, to 88.57% calcium carbonate with'an increase in recovery f rom'78.9%t o 84,5%. i ,f Example 1V -A number of assisting-reagents in addition'to thosey describedin Examples'II and III were tested underfthe same-conditions`outlined ingthe `control' run-(Ex-ample I) using'0.05;lb./-ton crude dodecylamine hydrochloride Hand .0.14 .1b./ton frotherb.` For sake of' brevity, typical results 'arelisted inthe accompanying tablet` f mh `Ier cent CaCO; Cacos Assistantv used, f .perpent ,lh/ton Heads Undemow recovery None (condon .meVv l t. acay L y i 8.9 -Sodium I cellulose {Ily l I 7 Mesquite gum.-.... 0.50 69,8 87.90 86.3

Cherrygum 0.50 70.3 86.50' 86.5

The above variations in the analyses of the heads are due to the differentbatchesof` limestone used for the-tests. s s;

Example V-(tc'tmtrol) ciunn"carbonate` content (80.81%) from* another source. 'Iheexperiment described herein is Aalso intended to Iillustratethe results obtained -in the absence of afria'ssistiiig"agent and for :comparison with' subsequentg examples Vwhere an" "assisting agent is used. The collector crudedodecylamine hydrochloride, was increased-to 0.10' Ibi/ton. and the frother b was used" in" a slightly' smaller fractions were filtered, drfedjwei'gh'ed and an` are summarized in the following'tabler:

Product Wight Percent g. recovery.

60.3 206.6 sans 1115.8 1 I7 Undernow I`V791.0, v 66.60 684.6 ses' l Calcd.

frother b, 0.11 lb./ ton.

The V abo've results vindicate that .thei grade l of.

the limestone (heads)v was increased from 80.3%"

to86.50%: calcium carbonate with a recoYery table below, but-usingless than half the quantity `'of collector fwith the following results: 1

Amt'- lfercent CaCO. Cacol l 'Weight Pr 6em."

4- Vi'lLcontrol'run similar to that described-"iri'f-Ex- 25 ample'il was made using 0.20 g. of 2-'ethylheXY1- 5" I .'Ihis experiment represents a control run which isjto b e compared with following Example which an assistant is used.

l'The process of Example V11 wasrepeated with tions were ltered, dried; weighed and'an'alyz'ed 10' as before.' The results are ys'un'l'marlzed-Hin the @was table l amount. For purpose;'ofcomparisonino=assistg i ant was usedin this control run. Theotation Y. l i Product Weight lyzed las usual. The results v,of `thisneiperimen't Percent Wght Percent recovery Rawie-collector, moin/ton; gun tragacanrh, cabin/c6112? Example IX of lifiother b. The resultingj-well-loaded.-gray -frctirwas collected for 9 minutes. 4 Thectatiqn given in the accompanying table:

Assistant used, par cent Starck.-." 0.50 81.8 91.50 84.8 Gum arabic. 0.50 $80.2 .96.30 83.0 Citrus pectin A0. 20 80. 4 93. 70 82. 4 Irish inoss Y 0.20 80.6 90. 10 87.1y Ammonium alginate .0.20 `80.1 .93.20, 88.3 Ifalnletto gums 0.20 7`8. 1 94.97 88.0

Thefpocessl of AExample I wasl repeated using u a collecting agent 4oi' the cationic surface active `A1typefpurermred `from the chloracetate of' the m-ixf'ture of ybranched chain alcohols vboiling at 160 'ffl-io' '195110. at atmospheric pressure, produced Vby i cataiytichydrogenation ofcarbon oxides,'in com r Hbiriationwithpyridine. 'Four cubic centimeters of al'5%"solution of the above' pyridine compound i was added to the slurry described in Example'I.

A heavlly *loaded',-gray` froth was produced'and collectedffora periodici'l 91minutes; The frac; tions werffiltered, dried, 'weighed and' analyzed. The results-aref-summarized inthe following 45 The4 process ofvExample IX wasrlrepeatedfwizth rt-isapparent that the addition'of tannicacia @increases the amount of 'overflow as compared 05 withthcontrolrun in `Eli'raxiiple IX.v The grade vof the underow was increased from '81.68% to 93.33% calcium'carbonate with a slight decrease in` recovery which could be increased by a.-I cleaner operation at noiappreciable decrease-'in grade.

The` following example, in which v'no assistant was used, is presented with a view to demonstrat- 'ing .theeectiveness of` an lassisting agent which 75 was used in the subsequent'E'xample' tailings; was treated with brokendownwith a; mixer Exam-ple XI was compared with those words., the quality oiy sentedl by 41.2%

` when. an assistant 'A slurry of 100- g. of Minnesota. iron ore washerv 0.015 g.. crude dodecylamine hydrochloride and 0.009- g. frother b. The. resulting. froth was collected for 6- minutes', and then recleaned. with 0.00319. crude dodecylaminehydrochloride and 0.009.- g.. frother b.. The fractionsv were. nltered, dried., weighed, and analyzed for the-'hwdroChI'Oric-acid soluble content,vwhich is. a measure ot iron content. The results are tabulated l Rougher operation- 0-.30- lbJton dodecylaminel hydrochloride- 0.18lb./ton frother. h- Cleaner operation- K I 0 061lb./ton dodecylamine hydrochloridev .0-.18 lb-./tonf.rotllery b Ema-molex!! To' demonstrate-the improved grade of underdow obtained withan assistant', the process. of repeated. using, in. addition to the exact amounts of dodecylami'ne hydrochloride 'and irother b, 0.025 g. gum tragacanth.. The iractions were illtered, dried', weighed.. and analyzed. The results are summarized in the following table: t

Product Wight Per cent Distribution Heads 100. (ll 3l. 5 100.0

. Rougheroverilow- 48. 5 10. 3 ll 8= Cleaneroverilow..- 4211. K 7 4- 9 8 Rougherfunderilow. 51.5 4 .5l-.l5y 84.2 Cleaner underiiow 6.4 29.9 6.0

v Comhlnedzunderilow'. l. 57.9- 49,-1. 90.2

-Reagcn tn Roughen operation- 0:30y lb /ton. dodeeylamlne hydrochloride 0 18lb./ton frother, b

v Cleaner operation- 1 0.06 lb./ton dodecylamine hydrochloride 0.18 lb./tonfrother b The addition of gum tragacanth improved the 11o-tation operationby giving rougher and combined. in'iclerilowsv of higher soluble content as in Example XI; Brother underflow .has been increased from. that repre- (Exampl'e XI to 49.1% soluble contenti.. It goes without saying; that the lower the hydrochloric acid-solublecor-ment,y the higher the insoluble.- silica content. It is' 'apparent from Example m and. XII that'. the silica rejection is increased is used: with a-f cationic collector..

In place or the water-solublev protectiveV col- 'loids listed in the above examples.. othersl may be substituted with equally good results.. Additional suitable agentsinclude water soluble. ammoniumand' amine salts of cellulose glycollic acid, glucaf methylstarch, agarV agar.. locust. bean. gum, water-solubleethyl cellulose,. hydroxyethyl. cellulose, water-soluble methyl" cellulose.. algini'cf and tannic water-soluble salts4 of pectic.

ironv oxidev in the combined" soluble content in. the control..

acid.. Jsmi-mmesai inclu-de man metal.. snrmoni'um and amine salts.. e.. g. mono. diand tri methyl. ethyl', propyl, isopropyl.. butyl.. etc. salts'.

In addition to the specificcationic surface ne# tiveagen-ts disclosed in th examples; found that a very large number of other agenti of this type will give good. results. Either. single compounds or mixtures are: useful- Among the agents which can bey used toadvantage inthe :epf-

aration of metal carbonatos oxides' from.

silieeousl genaues, the following may be-mentioned ride v Dodecylv trimethyl ammoniumbromide or chloride Octadecyl trimethyi bromide or chloride Hexadecyl trimeth-yi ammonium bromide: or chlo- Hexadecyl pyridinium bromide or' chloride Dodecyl. pyridinium bromide or chloride Dodecylaminehydrochlorid hydrobrcmlde'... nitrate, acetatesor chloroacetate Hexadecyl'aminehydrochloride Octadecylam'ne. hydrochloride.

Dodecyl dimethyl su'lf'onlum methyly sulfate'. Dodecyldimethyl s ultonium bromide Octadecyl. methyl ethyl. su'I-phonium iodide. Tetradecyl. dimethyl. sulphoniuxn bromide Dodecyl methyl .cyclohexyl su-lphonium lodi-"de Doclecyly benzyl methyl sulphoniurrrchloride Alargelist of useful ammonium, vsulphouiuxn l` andl phosphonium. compounds which have utility inthe herein disclosed processesv are set'. forth I in Dunbar U. S. Patent 2,165,355..

` The agents ci" our inventioxl-.maybe'designlted j I by the following l ieneral formula:

R-Mmlz-Y v in. which. R' 4isl a norr-aromatic:v (i. e. noubenzenoid) hydrocarbon. radical' of sito; 22 carbon. atoms; M represents pentavalent nitrogen-pens tavalent. sulfur., or tetravalent sull-ur:- B" representa hydrogen' atoms or hydrocarbon havingv not more than 5 carbon xvi/.toms` be constituents of an alicyclic: or ot aheterocycllc ring: :c is anintoger' lessiby two the of elementv M, and Y' is a. negatively charged nit 1f formingy atom] or group'. for example"r chlorine,

bromine; ni'ln'aie'-,Y acetate, chloroacetate.. etc, The long chainv aliphaticradical R neednot'v be entirely composedof carbon atcxnsin-I the chainy but may contain ether linkages, esterV groups,'sul

furl atoms'. carbonyl. groups., ete'. presided. these groups do not introduce. new centersy of. polarity.. For example. reagentssuch as the-hydrochloride of. the dodecyl ester* oi alpha-@aminosobut'yric acid, the hydrochloride ot betasrtrnllsioeth'lf'A dodecyl eener. and; me hydrochloride of' dodecyl ester of alpha-aminisobutyrlcf good. flotation. reagents. forA use-im process: ol-

f thisy invention; such substances.; however, asf the hydrochlorides of' o..k longy amine a. carboxyl group. on the emsl"v from the' amino group would not. produce.'- the: destred e2- rect,4 since another polar;v sol'ubilizim,` group hasi .l y. vv

been. introduced.

` Two other typesaoi'cationic.surfaceactivezre *agentsA which hear lsome mention. are found we.' fnl in the practice of. this. invention. Onev of these types comprises salts4 oi amlnonaphthenel derived from naphthenlc acids? of. 12. to v20; etrbolrv atoms and natural acidicresins.. e'. g.. Congo, kauri,. Manila; san-diamo.. damn'. Pone-- tianac, Zanzibar; etc. The aminonaphthenes can be made by catalytically dehydrating the acids `in the presence of ammonia and subsequent reduction of the nitriles to the corresponding amines and the salts can be made by treating the amines with an acid, e. g. hydrochloric. 'I'he reactions involved are discussed below in connection with higher fatty acids.

The second class which appears to differ from the type formula are the betaines having long aliphatic chains. Some illustrative betaine type compounds apparently have the following formula, although there is some evidence in favor of their being non-cyclic compounds:

CH: CH: v

R-CHa- C-R wherein one of the Rs is a long chain aliphatic hydrocarbon radical and the other R hydrogen The preparation of these compounds and specific examples of related compounds useful in this invention is given in Downing and Johnson U. S. Patent 2,129,264. Examples of such betaines are N-dodecyl betaine, N-cetyl betaine, N-decyl betaine, C-dcdecyl betaine, C-octadecyl betaine, etc.

The betanes are particularly effective if used in the presence of small amounts of mineral or organic acids and this observation may-furnish a clue to their manner of action. It is possible that the betaine ring tends to open by addition of acid and the resulting product tends to ionize yielding a surface active cation.

A class of substances which we have found to be particularly effective is composedv of mixtures of salts of amines derived from the fatty acids' obtained by hydrolytic splitting o f natural fatty glycerides. e. g. palm oil, coconut oil, stearin, etc. 7

For example, the mixture of amines derived from l coconut oil fatty acids by the following series of4 reactions such as follows gives excellent otation results after conversion to a water-soluble salt such as the hydrochloride or acetate.

. ton of ore, but in some cases somewhat smaller or'larger' quantities may be required. The amount of protective colloid of the carbohydrate type used may also vary widely. In general from 0.01 to 5.0 pounds of assistant per ton of ore is satisfactory, but for most cases from 0.2 to 1.0 pound per ton is suicient. Some of the reagents produce sumcient frothing so that an additional frothing agent is not required, while others have little or no frothing power. When greater frothing power is needed, we prefer to use a material such as pine oil, cresyiic acid or frother b, since these frothers have no adverse effect on the selectivity of the collecting agents. Occasionally we find it advantageous to use mixtures of two or more of the cation-active reagents to produce flotation products of high quality. In carrying out a flotation process according to the teachings of this invention, any of the well known types of flotation cells maybe employed.l The ratio of pulp solids to -water may vary from'about 1:1 to 1:6. Ordinarily a neutral pulp is` used, but in some cases'it may be desirable to use an alkaline or acid pulp. c

It will be clear from` the above that one of the uses of this invention'is the preparation ofcalcium carbonate of good quality from natural rocks whose calcium carbonate content is too low to be of technical value. By means of this process limestone rocks containing I0-70% calcium carbonate can be purified to su'ch an extent that the product can be used in the manufacture of Portland cement. It is also possible to prepare calcium carbonate concentrates approaching theoretical purity from low-grade limestone by this process. 'I'he process of this invention also permits the recovery of iron carbonate, manganese carbonate, magnesium carbonate, and other metallic carbonates from ores containing these minerals with other siliceous materials as impurities. Conversely it may be used to prepare talc, mica, or quartz products of high purity and value when the principal impurities are alkaline earth or heavy metal carbonates or oxides. While the herein disclosed examples apply to the use of assistants in the beneficiation of calcium carbonate, the same principles apply to the concentration of oxidized iron minerals in which the cationic surface active collectors are beneted through the use of the water-soluble protective colloid assistants of the carbohydrate type.

The present process affords two outstanding advantages as ,compared with previously known methods for the removal of siliceous minerals by means of cationic surface active agents as collectors. First, it provides a process by which quartz and siliceous minerals can be separated from other minerals at a substantial reduction in the amount of collector through the use of assistants. Secondly, with a given amount of cationic surface-active agents, the use of an assistant increases the selectivity as a result of which a higher grade of mineral concentrate is obtained. In general, processes for the flotation of ores containing negatively charged minerals by means of cationic surface agents as collectors are improved by any one of the protective colloid assisting agents described herein.

This application is a continuation-impart of co-pending application Serial No. 169,072, filed October 14, 1937.

While the preferred embodiments of my invention have been disclosed, it will be readily apparent to those skilled in the art that many variations and modifications may be made therein without departing from the spirit of the invention.

I claim:

l. A froth flotation process for concentrating ores containing negatively charged gangue materials taken from the group consisting of metal carbonate and oxide ores which comprises adding to an aqueous pulp of such vores a cationic surface active agent and a small amount of a water soluble substance taken from the group consisting of tannc, pectic, and alginic acids and their water soluble salts. i

2. A froth flotation process for concentrating ores containing negatively charged gangue materials takenfrom the group consisting of metal carbonate and oxide ores which comprises adding to an aqueous pulp of such ores a small amount of an alkyl amine salt wherein said alkyl radical contains from 8-22 carbon atoms and a small amount of a water solublel substance to an aqueous pulp of such ores a small amount taken from the group consisting of tannic, pectic, of dodecylarnine hydrochloride and a small l and alginic acids and their water soluble salts. amount of a water soluble substance taken from 3. A froth flotation process for concentrating the group consisting of tannic, pectlc, and alginic f ores containing negatively charged sangue ma- 5 acids and their water soluble salts.

terials taken from the group consisting of metal carbonate and oxide ores which comprises addinz JAMES EMORY KIRBY. 

